Can someone summarize, with references if possible, all of the alternatives to the simplest model (that requires only a single scalar Higgs field with the Mexican Hat potential) of spontaneous electroweak symmetry breaking?

The FAQ says "ask practical, answerable questions based on actual problems that you face." Does your question fit this criterion?
–
phoFeb 12 '11 at 22:38

6

The question is practical and answerable for someone who is working in particle physics and is familiar with the Higgs mechanism and its alternatives. I'm guessing a competent phenomenologist would be. It's also an "actual problem I face" because I'm studying the Standard Model and want to know what the best alternatives to the Higgs mechanism are.
–
dbraneFeb 12 '11 at 22:47

They are called 'Higgsless' models and you can google for the appropriate model. I vote to close this topic absent something more specific
–
ColumbiaFeb 12 '11 at 22:48

1

You asked for "all" not "best". There are many alternatives to the simplest model: 2 Higgs fields, 3 Higgs fields ad infinitum; technicolor models; Susy models, top condensate models, little Higgs, Higgsless and so on and so on with hundreds of papers on each topic. This is way too broad a question to expect a short useful answer.
–
phoFeb 12 '11 at 23:05

2

@Jeff, @dbrane, @Columbia: Since there are so many approaches, maybe it would be best to make this a community wiki, so that everyone can put down their favourites.
–
SimonFeb 13 '11 at 0:00

3 Answers
3

I'm pretty sure that even the brief summarization of all the alternatives will take a book or two. I will try to give a review of basic things from my perspective. Let me from the beginning note that the following classification is not accurate -- different classes may and do overlap.

More scalar doublets (multiplets)

First of all one can introduce more scalar multiplets. Two Higgs doublet model (2HDM) is the most favored, because it is also naturally arises from MSSM. NHDMs are also considered.

Doublets are usually considered, because there is a basic constraint on the quantum numbers of the fields, coming from "rho parameter":

$\rho = \frac{M_W^2}{M_Z^2\cos^2\theta_w}=1$

Which can be satisfied only if $(2T+1)^2-3Y^2=1$ with the most natural solution $Y=1,T=1/2$. Of course there are other solutions, leading to bigger values, but I've never seen anyone seriously considering those.

There is still a lot of freedom to impose some extra discrete symmetries, continuous symmetries, the way these scalars interact with fermions, e.t.c., which leads to many subclasses of such models.

Composite Higgses

The central example is the Little Higgs model where Higgs arrives as a (pseudo-)goldstone boson from some higher global symmetries. Changing the underlying symmetry one obtains the whole class of such models.

Extra gauge symmetries are also considered -- they are usually broken dynamically. Technicolor was the most popular one -- now it not so favored, while I don't think that it was refuted completely. Top condensate is another dynamical model.

Originated from extra dimensions

Lots of geometries, compactifications, boundary conditions -- I feel completely lost with those. Most popular are higgsless models -- attempts to get rid of Higgses completely. They are usually based on some specific boundary conditions.

Of course the list in incomplete. There are a lot of different "mixtures" between those models, usually with some new funny names.

Here is a nice recent reference that reviews some of the mentioned models going more deeply into some tehnical details.

There is an important alternative to the Higgs mechanism. This will be explained by first stating that photons are only massless particles when they are freely propagating. If a photon is confined to a specific volume, for example in a hypothetical reflecting box, then the photon is forced to adopt the frame of reference of the box and the confined photon exhibits the same inertia as a mass with equal energy. If there was any difference in the inertia of energy in two different forms, this would be a violation of the conservation of momentum. The explanation is that confined light exerts uniform photon pressure on the walls of the box when the box is at rest. However, when the box is accelerated there is a Doppler shift on light propagating opposite directions and more pressure is exerted on the rear wall than on the front wall. The difference is a net force which exactly equals the force that accelerating a mass of equal energy would generate. Any confined energy propagating at the speed of light generates this inertial force without the Higgs mechanism. A particle model incorporating dipole waves in spacetime has been proposed ( http://onlyspacetime.com/ ) and it generates exactly the correct inertia.

This model is based on John A. Macken´s proposal,[2] that universe is only spacetime and can be seen as a sea of energetic waves (Dipole Waves), traveling at light speed.

From Macken´s Dipole Waves (DW model), Policarpo Y. Ulianov [5] defines a fundamental particle, named Ulianov Hole (uhole),[3][4] that can seems as an elastic tube that connect two points in spacetime, changing the DW high pressure (~10^113 J/m3).

There is two kinds of Uholes: The Uhole-S that has a mass property; The Uhole-T that has an electric charge property.

The Uhole-S Model can be an alternative to the Higgs field mass generation mechanism,[1] enabling some simple deductions of Newton´s laws, associated with matter, and also explains the fact that the inertial mass is equal to gravitational mass.